Clinical Parameter for Deciding the BRAFV600E Mutation Test in Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance Thyroid Nodules: US Features According to TIRADS

This study aimed to investigate the usefulness of a thyroid imaging reporting and data system (TIRADS) to select thyroid nodules with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) cytology for additional BRAF^V600E mutation testing. Three hundred three thyroid nodules were included. Statistical analysis was performed at both patient and nodule levels according to BRAF^V600E mutation positivity and clinical factors. Univariate and multivariate logistic regression analyses were performed to assess independent associations between BRAF^V600E mutation positivity and clinical factors. Of 303 AUS/FLUS nodules, 16 (5.3%) of 303 nodules had the BRAF^V600E mutation. The frequency of the BRAF^V600E mutation according to the TIRADS was 35.7% for category 5, 10.8% for category 4c, 2.5% for category 4b, 1.1% for category 4a, and 0% for category 3 nodules (P < 0.001). On multivariate analysis, BRAF^V600E mutation positivity was significantly associated with high suspicion on the TIRADS (odds ratio, 15.247; P < 0.001). In conclusion, the ultrasonography patterns of the TIRADS can be used as a clinical parameter for deciding the BRAF^V600E mutation test in thyroid nodules with AUS/FLUS cytology.